Load anticipating engine/transmission control system

ABSTRACT

An engine and transmission control system is responsive to manipulation of manually operated control devices which can cause actions which result in increased load on the vehicle engine, before the engine actually begins to be effected by the load increase. The control system monitors manipulation of control devices and engine load, and when engine load decreases, the system stores the identity and displacement direction of the manipulated control device. When the same control device is then manipulated in the opposite direction, the control system will begin to temporarily boost or raise engine rpm and decrease the transmission ratio in anticipation of the expected load. After the control system has boosted the engine rpm, it monitors whether or not the engine speed was boosted high enough to prevent the engine speed from dropping below a threshold. If the engine speed drops below the threshold, then the control system will increase the amount of engine speed boost to be applied the next time that control device is manipulated.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of applicant's co-pending applicationU.S. Ser. No. 10/457,223, filed 9 Jun. 2003 and titled LOAD ANTICIPATINGENGINE/TRANSMISSION CONTROL SYSTEM, which application is pending.

BACKGROUND

The present invention relates to an electronic engine and transmissioncontrol system which is responsive to manipulation of manually operatedcontrol devices which can cause actions which result in increased loadon the vehicle engine.

There are production agricultural tractors which have an electronicallycontrolled engine and electronically controlled transmission, such as aninfinitely variable transmission (IVT). Such a tractor can be operatedin a fuel economy mode wherein the engine is controlled to run at a lowengine speed. If, while in this mode, the operator manually commands thehitch to drop a hitch-mounted implement into the ground, or if theoperator commands the ground-engaging elements of a towed implement,such as a ripper, to engage the earth, the tractor may stall because thetransmission and engine cannot react quickly enough to overcome theincrease in load. This can happen when such a tractor is being turnedaround at the end of a field and then driven a short distance at the endof the row. Then when the tractor is driven back into the field and theimplement is dropped into the ground, the tractor may stall because theengine speed is too low.

SUMMARY

Accordingly, an object of this invention is to provide a system whichprevents engine stalling as a result of the performance of manuallycontrolled operations which increase the load on the engine.

A further object of the invention is to provide such a system whichautomatically boosts engine speed for a short time period in response tomanipulation of an implement control device before operation of theimplement increases the load on the engine.

These and other objects are achieved by the present invention, whereinan engine and transmission control system is provided for avehicle/implement system having manually operated control devices whichare used to control hitch-mounted and/or towed implement operations. Thecontrol system monitors manipulation of the control devices and engineload, and when engine load decreases, the system stores the identity anddisplacement direction of the manipulated control device. When the samecontrol device is then manipulated in the opposite direction, thecontrol system will temporarily boost or raise engine RPM and decreasethe transmission ratio in anticipation of the expected load. After thecontrol system has boosted the engine rpm, it monitors whether or notthe engine speed was boosted high enough to prevent the engine speedfrom dropping below a threshold. If the engine speed drops below thethreshold, then the control system will increase the amount of enginespeed boost to be applied the next time that control device ismanipulated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified schematic diagram of an engine control systemaccording to the present invention;

FIG. 2 is a simplified overall logic flow diagram illustrating analgorithm executed by the ECU of FIG. 1;

FIG. 3 is a logic flow diagram of the lever check subroutine portion ofFIG. 2;

FIG. 4 is a logic flow diagram of the heavy load calculation subroutineportion of FIG. 2;

FIG. 5 is a logic flow diagram of light load calculation subroutineportion of FIG. 2; and

FIG. 6 is a logic flow diagram of the boost calculation subroutineportion of FIG. 2.

DETAILED DESCRIPTION

Referring to FIG. 1, an engine 10 drives a transmission 12, preferablyan infinitely variable transmission (IVT) which drives a vehicle wheel13. The engine 10 is controlled by an electronic engine controller 14,and the transmission 12 is controlled by an electronic transmissioncontroller 16. Controllers 14 and 16 are communicated with an auxiliarycontroller 18 via a conventional CAN bus. Controller 18 may be mountedin a vehicle armrest (not shown). An implement interface unit 17communicates hydraulic valve command signals from an implement 19, suchas a towed implement, to controller 18.

Controller 18 receives command signals from a plurality of operatormanipulated input or function control devices 20A-20D, such as paddlepots or selective control valve (SCV) levers for controlling (viahydraulic controller 32) selective control valves (SCV) 24A-24D, and ajoystick 22 for controlling selective control valves 24E and 24F, and aconventional hitch control lever 26 and lever position sensor 28 forcontrolling a hitch control valve 34. SCVs 24A and 24B may controlhydraulic cylinders 36A and 36B located on the implement 19. Hydrauliccylinders 36A and 36B control ground engaging elements 37A and 37B onthe implement 19. SCVs 24C-24F may control other hydraulic cylinders36C-36F. Controller 18 also receives signals from an auto mode switch30, and hydraulic valve commands via interface 17 from control devices(not shown) which may be located on the implement 19. Auto mode switch30 is preferably a multi-position switch which the operator canmanipulate to select different desired maximum engine speed when thetractor is operating under light load conditions. For example, switch 30may be used to select mode 1=fuel economy off, mode 2=1500-1800 rpm, ormode 3=1200-1500 rpm. Paddle pots 20 and lever 26 are movablefore-and-aft to plus and minus positions on opposite sides of a centeror neutral position to extend or retract a corresponding hydraulicfunction or hitch cylinder 38. A paddle pot or SCV lever is described indetail in U.S. Pat. No. 5,343,775, issued in 1994 and assigned to theassignee of this application.

Hydraulic controller 32 provides control signals to selective controlvalves (SCV) 24A-24F and to hitch valve 34. Controller 32 is preferablycapable of executing implement management system (IMS) algorithms, suchas described in U.S. Pat. No. 6,292,729, and preferably transmits IMSsignals to controller 18. Hitch valve 34 controls a hitch cylinder 38which raises and lowers an implement hitch 39 to which an implement 41is attached. The controllers 14, 16, 18, 32 and interface 17 arepreferably connected to each other by a conventional CAN bus. Inresponse to the signals it receives, controller 18 generates andprovides control signals to the hydraulic controller 32.

An engine speed sensor 40 provides an engine speed signal ES tocontroller 14. A wheel speed sensor 42 provided a wheel speed or vehiclespeed signal WS to controller 16. The auto mode switch 30 providesselected desired engine speed signals to controller 18 for use when in alow engine speed mode. The system hardware components described so farare similar to those found on commercial 7810 Series John Deere tractorswith an IVT.

The controller 14 provides engine speed signal ES and an engine loadsignal L to auxiliary controller 18, and controller 16 provides wheelspeed signal WS to controller 18. Controller 18 executes an algorithm100 and generates a Desired Engine Speed Command and a TransmissionRatio Command in response to the signals it receives. This algorithm 100is executed periodically, such as 50 times per second, and isillustrated by the flow chart of FIG. 2. Algorithm 100 sequentiallyexecutes a read CAN messages step 200, a lever check subroutine 300, aheavy load control calculation subroutine 400, a light load calculationsubroutine 500, a boost calculation subroutine 600. At step 700, thecontroller 18 transmits a Desired Engine Speed Command over the CAN busto the engine controller 14, and transmits a Transmission Ratio Commandover the CAN bus to the transmission controller 16.

In step 200, the controller 18 reads and stores a plurality of inputsignals. It reads the vehicle speed from sensor 42, engine speed fromsensor 40, engine load from controller 14, commands from SCV controldevices 20A-20D and the joystick 22, hitch command from sensor 28, IMScommands from controller 32, control valve commands from interface 17,requests for increased hydraulic flow from implement 19 via theinterface 17 and requests for increased engine speed from implement 19via interface 17.

Referring now to FIG. 3 and lever check subroutine 300, step 302 sets anSCV_NUM index value to zero.

If a request for increased engine speed has been received via interface17, step 304 directs the subroutine to step 306, else to step 308. Step306 sets a BOOST TIMER value to 0.1 seconds and sets anENGINE_FLAG=true, and directs the subroutine to step 526 of subroutine500.

Step 310 compares SCV_NUM to the total number of input control devices.If SCV_NUM is not less than the total number, step 310 directs thesubroutine to step 322 which directs control to subroutine 400. IfCV_NUM is less than the total number, step 310 directs the subroutine tostep 312 which increments SCV_NUM.

Step 314 compares the command value for the control device correspondingto the current SCV_NUM value to a threshold, T, representing a neutralor center control device position. If the command value equals T(representing a neutral or center control device position), step 314directs the subroutine to step 316 which sets a control device directionvalue (LEVER_DIR) equal to zero, sets an control device number value(LEVER_NUM) equal to zero, and then returns control to step 310.

If the command value is greater than T (the control device is in a plusposition), step 314 directs the subroutine to step 318 which sets acontrol device direction value (LEVER_DIR) equal to 2, sets the controldevice number value (LEVER_NUM) equal to SCV_NUM, and directs control tostep 322. If the command value is less than T (the control device is ina minus position), step 314 directs the subroutine to step 320 whichsets a control device direction value (LEVER_DIR) equal to 1, setsLEVER_NUM equal to SCV_NUM, and then returns control to step 322. Step322 directs control to subroutine 400.

To summarize, the lever check subroutine 300 first checks if animplement function is demanding an increased engine speed. If animplement function requests an increased engine speed, then thesubroutine sets the BOOST TIMER and ENGINE FLAG. This will cause controlto skip the heavy load subroutine 400 and jump to the light loadsubroutine 500 (to the step where the BOOST TIMER is checked).

Otherwise, the subroutine 300 checks for commands indicating adisplacement of each of the hydraulic control devices, including the SCVlevers 20, joystick 22, hitch lever 26, or a control device which wouldcause interface 17 to transmit a valve command to controller 18. If oneof these commands indicates a non-centered control device position, thesubroutine stores the LEVER_DIR (direction of displacement) andLEVER_NUM (the identity of the displaced control device), and thendirects control to subroutine 400. If no command indicates a displacedor non-centered control device, control passes to subroutine 400.

Turning now to FIG. 4 and the heavy load control calculation subroutine400, step 404 compares the engine load L and the wheel speed WS tocertain values. Step 404 directs the subroutine to step 412 if theengine load is greater than or equal to 80% of a maximum load value andWS is greater than or equal to 1 kph. Step 404 directs the subroutine tostep 406 if the engine load is less than 80% of maximum or WS is lessthan or equal to 1 kph.

Step 406 sets a load control on timer value (LC ON TIMER)=0.

Step 408 checks the status of a load control SCV timer value (LC SCVTIMER). If LC SCV TIMER=0, step 408 directs the subroutine to step 422.If LC SCV TIMER>0, step 408 directs the subroutine to step 410.

Step 410 sets the LC ON TIMER to 0, sets a SCV_MOVED flag=true, sets aFE ON TIMER value=10 seconds, sets the LC SCV TIMER=0 seconds, anddirects the subroutine to step 422.

Returning to step 412, step 412 increments the LC ON TIMER, after whichstep 414 checks the status of the LC ON TIMER. If LC ON TIMER >=20seconds, step 414 directs the subroutine to step 416. If LC ON TIMER<20seconds, step 414 directs the subroutine to step 422.

Step 416 checks the status of LEVER_DIR and LC_SCV_TIMER. If LEVER_DIR>0and LC_SCV_TIMER=0, step 416 directs the subroutine to step 418. IfLEVER_DIR=0 or LC_SCV_TIMER>0, step 416 directs the subroutine to step420. Step 418 sets SCV MOVE DIR to LEVER_DIR, sets SCV MOVENUM=LVER_NUM, sets LC SCV TIMER=5 seconds and directs the subroutine tostep 420.

Step 420 decrements the LC SCV TIMER and directs the subroutine to step422. Step 422 directs control to subroutine 500.

To summarize, the heavy load control calculation subroutine 400 checkswhether the tractor is moving at a minimum speed (1 kph) and whether theengine is being heavily loaded (over 80% maximum engine load). If thetractor is heavily loaded and is moving at or faster than the minimumspeed for less than 20 seconds, the algorithm proceeds to the subroutine500.

If the tractor has been under heavy load and is moving faster than 1 kphfor 20 seconds and a control device is displaced, then the identity ofthat control device (SCV MOVE NUM) and its direction of displacementfrom its centered or neutral position (SCV MOVE DIR) is stored. If theengine load drops or the tractor slows below 1 kph within a short amountof time (5 seconds) after the control device has been displaced, thenthe SCV_MOVED flag is set equal to true to indicate that the storedcontrol device caused that decrease in the engine load.

Turning to FIG. 5 and light load calculation subroutine 500, step 504checks the operational status of the Fuel Economy mode as represented bya Fuel Economy Mode flag. This flag is initially false (the first timethe algorithm is executed), and is then set true or false at steps 536 &538. If the Fuel Economy mode is not on, the subroutine proceeds to step508 which sets an RPM Setting value=minimum engine speed, and then tostep 540 which sets Transmission ratio=desired wheel speed÷rpm setting,and then directs the algorithm to subroutine 600. If the Fuel Economymode is on, the subroutine proceeds to step 506 which sets the LC ONTIMER=0 seconds.

Next, step 510 checks the FE ON TIMER. If FE ON TIMER>0 seconds, step512 decrements the FE ON TIMER and directs the subroutine to step 520.If FE ON TIMER=0 seconds, step 510 directs the subroutine to step 514.

Step 514 checks the SCV_MOVED flag. If the SCV_MOVED flag is false, step514 directs the subroutine to step 520, else to step 516.

Step 516 whether the stored LEVER_DIR is opposite of the SCV MOVE DIR,whether SCV MOVE NUM=LEVER_NUM, whether WS>=1 kph, and whether BoostTimer=0. If these conditions are all true, the subroutine proceeds tostep 518, else to step 520.

Step 518 sets the SCV_MOVED flag=false, resets SCV MOVE DIR, resets SCVMOVE NUM, sets the Boost Timer=3 seconds and directs the subroutine tostep 520.

Step 520 checks the Boost Timer. If the Boost Timer=0 seconds, step 520directs the subroutine to step 522 which sets RPM Setting=minimum enginespeed, and then returns at step 534. If the Boost Timer>0 seconds, step520 directs the subroutine to step 524 which decrements the Boost Timerand directs the subroutine to step 526.

Step 526 checks the status of Auto Mode switch 30. If the Auto ModeSetting=Mode 2 then step 528 sets the RPM Setting to Boost 1, such as1500 rpm. If the Auto Mode Setting is other than mode 2 or 3, then step530 sets the RPM Setting to a maximum engine speed value. If the AutoMode Setting=Mode 3 then step 532 sets the RPM Setting to Boost 2, suchas 1800.

Following steps 528, 530 and 532, step 534 checks the engine load andRPM Setting value. If engine load is <80% of what maximum fuelconsumption and RPM Setting>a minimum engine speed, then step 536 setsthe Fuel Economy flag=true. If engine load is >80% or RPM Setting<aminimum engine speed, then step 538 sets the Fuel Economy flag=false.

Step 540 then sets Transmission Ratio=desired wheel speed÷RPM Setting,sets Desired Engine Speed Command ═RPM Setting, and then directs thealgorithm to step 600.

To summarize, the light load subroutine 500 operates when the vehicle isunder light load. If the SCV_MOVED flag is true, and the stored controldevice is subsequently moved in the opposite direction to the storeddirection, then steps 516 and 518 of subroutine 500 will operate tocause an immediate 3 second engine speed boost, even before the enginewould otherwise detect the increased load which would eventually resultfrom such input displacement. subroutine 500 also determines an enginerpm setting value as a function of the setting of the auto mode switch30. Subroutine 500 also determines a transmission ratio value as afunction of a desired wheel speed and the engine rpm setting value, andsets an engine speed command value equal to the rpm setting value.

Turning to FIG. 6 and boost calculation subroutine 600, step 602 checksthe Boost Timer and the engine speed ES. If Boost Timer>0 andES>=(Desired Engine Speed Command−30 rpm), then step 604 sets a LugdownTimer=5 seconds and directs the subroutine to step 606. If Boost Timer=0or ES<(Desired Engine Speed Command−30 rpm), then step 602 directs thesubroutine to step 606.

Step 606 checks the Boost Timer and the Lugdown Timer. If Boost Timer=0and the Lugdown Timer>0, then step 606 directs control to step 608.

Step 608 decrements the Lugdown Timer and directs control to step 610.

Step 610 checks the engine speed ES. If ES>=a Low Allowable Engine Speedvalue, then step 624 returns control to the main loop 100. If ES<the LowAllowable Engine Speed value, then step 612 sets an Engine Dropped Lowflag=true, and sets a New Boost value=ES−Low Allowable Engine Speedvalue, after which subroutine 660 ends at step 624.

Returning to step 606, if Boost Timer>0 or the Lugdown Timer=0, thenstep 606 directs control to step 614. Step 614 checks the Engine DroppedLow flag. If the Engine Dropped Low flag=false, and the subroutine endsat step 624. If the Engine Dropped Low flag=true, then step 614 directsthe subroutine to step 616.

Step 616 checks the Auto Mode Setting. If Auto Mode Setting=Mode 2, thenstep 616 directs the subroutine to step 618. If Auto Mode Setting=Mode3, then step 616 directs the subroutine to step 622. If Auto ModeSetting=any setting other than Mode 2 or 3, then step 616 directs thesubroutine to step 620.

Step 618 sets Boost 1=Boost 1+New Boost, sets New Boost=0 and setsEngine Dropped Low=False and directs control to step 624. Step 620 setsNew Boost=0 and sets Engine Dropped Low=False and directs control tostep 624. Step 622 sets Boost 2=Boost 2+New Boost, sets New Boost=0 andsets Engine Dropped Low=False and directs control to step 624.

To summarize, the boost calculation subroutine 600, determines, when anengine boost is commanded, whether or not the boost commanded is largeenough to stop bad performance (such as engine stalling). Subroutine 600monitors the actual engine rpm after a boost is commanded, and if theactual engine rpm drops too low, then subroutine 600 increases the boostso that the next time a boost is commanded the actual engine rpm willnot drop too low.

Finally, referring again to FIG. 2, subroutine 700 causes the controller18 to transmit the Desired Engine Speed Command (from step 540 ofsubroutine 500) to the engine controller 14, and to transmit theTransmission Ratio command (also from step 540) to the transmissioncontroller 16. The engine controller 14 increases the engine speed ifcommanded by the Desired Engine Speed Command, and the transmissioncontroller 16 controls the transmission ratio of the transmission 12 inresponse to the Transmission Ratio command.

As a result, the engine and transmission control system reacts to acontrol device operation (such as commanding an implement to engage theground) which will increase engine load, before the engine actuallybegins to be affected by the load increase. To do this, the controlsystem monitors manipulation of manual control devices and learns whichcontrol device manipulations previously caused a decreased engine load.When the same control device is then manipulated in the oppositedirection, the control system will temporarily boost or raise engine RPMand decrease the transmission ratio in anticipation of the expectedload. The drop in transmission ratio will result in a constant wheelspeed. After the control system has boosted the engine rpm, it willmonitor whether or not the engine speed was boosted high enough toprevent the engine speed from dropping below a threshold. If the enginespeed drops below the threshold, then the control system will increasethe amount of engine speed boost to be applied the next time thatfunction control is manipulated.

The conversion of the above flow charts into a standard language forimplementing the algorithm described by the flow chart in a digitalcomputer or microprocessor, will be evident to one with ordinary skillin the art.

While the present invention has been described in conjunction with aspecific embodiment, it is understood that many alternatives,modifications and variations will be apparent to those skilled in theart in light of the foregoing description. For example, the invention isapplicable to a system having any sort of operator manipulated controldevices, such as levers, knobs, switches, buttons, etc. Accordingly,this invention is intended to embrace all such alternatives,modifications and variations which fall within the spirit and scope ofthe appended claims.

1. A control system for a utility vehicle having an engine, an enginecontroller for controlling the engine, and an earth engageable implementcoupled to the vehicle, the control system comprising: a manuallyoperable implement control device for controlling the implement; and anelectronic control unit (ECU) coupled to the engine controller and tothe implement control device, the ECU, in response to a manipulation ofthe implement control device, generating an engine speed boost signalwhich causes the engine controller to temporarily increase engine speedbefore the implement applies and increase load on the engine.
 2. Thecontrol system of claim 1, wherein: the vehicle also has a transmissiondriven by the engine, and a transmission controller for controlling thetransmission, and the ECU, in response to the manipulation of theimplement control device, provides a transmission control signal to thetransmission controller which causes the transmission to lower itstransmission ratio before the load on the engine increases.
 3. Thecontrol system of claim 1, further comprising: an engine speed sensorfor generating an engine speed signal, the ECU comparing the enginespeed to a threshold, and if the engine speed drops below said thresholdthe ECU increases an amount of engine speed boost for use a next timethe control device is manipulated.
 4. The control system of claim 1,further comprising: an operator controllable mode switch; and the ECUvarying an amount of engine speed boost in response to operation of themode switch.
 5. The control system of claim 1, wherein: the vehicle hasan implement hitch attached thereto; and the implement is an integralimplement attached to the hitch, raising and lowering of the implementbeing controlled by the control device.
 6. The control system of claim1, wherein: the implement is a towed implement, the implement having aground engaging element controlled by a hydraulic function controlled bythe implement control device.
 7. A control system for a utility vehiclehaving a transmission driven by the engine, an engine controller forcontrolling the engine, and an earth engageable implement coupled to thevehicle, at least one hydraulic cylinder operable to control engagementof the implement with the earth, the control system comprising: aplurality manually operable control devices, each for controlling acorresponding hydraulic function, including the at least one hydrauliccylinder, manipulation of a certain one of the control devices in afirst manner causing the implement to increase a load on the engine,manipulation of said certain control device in a second manner causingthe implement to decrease load on the engine; the engine controllergenerating an engine load signal; a plurality of position sensors, eachgenerating a control device position signal representing a position of acorresponding control device; and an electronic control unit (ECU)coupled to the position sensors and receiving the load signal from theengine controller, the ECU, in response to manipulation of one of thecontrol devices followed by a reduction in engine load, storing identityand manipulation manner information for the control device justmanipulated, and the ECU automatically temporarily boosting engine speedwhen the control device with the stored identity is later manipulated ina manner opposite to the stored manipulation manner, the ECU therebyincreasing engine speed before load on the engine increases.
 8. Thecontrol system of claim 7, wherein: the vehicle also has a transmissioncontroller for controlling the transmission, and the ECU, in responsemanipulation of one of the control devices followed by a reduction inengine load, storing identity and manipulation manner information forthe control device just manipulated, and the ECU automaticallytemporarily causing the transmission controller to lower thetransmission ratio when the control device with the stored identity islater manipulated in a manner opposite to the stored manipulationmanner.
 9. The control system of claim 7, further comprising: an enginespeed sensor for generating an engine speed signal, the ECU comparingthe engine speed to a threshold, and if the engine speed drops belowsaid threshold the ECU increases an amount of engine speed boost for usea next time the control device is manipulated in said opposite manner.10. The control system of claim 7, further comprising: an operatorcontrollable mode switch; and the ECU varying an amount of engine speedboost in response to operation of the mode switch.
 11. The controlsystem of claim 7, wherein: the vehicle has an implement hitch attachedthereto; and the implement is an integral implement attached to thehitch, raising and lowering of the implement being controlled by thecontrol device.
 12. The control system of claim 7, wherein: theimplement is a towed implement, the implement having a ground engagingelement controlled by a hydraulic function controlled by the implementcontrol device.
 13. In a vehicle having an engine driving wheels througha transmission, a plurality of engine powered auxiliary functions, theoperation of each auxiliary function being controlled by a correspondingmanually operated control device, a method of controlling the enginecomprising: monitoring engine load; monitoring displacement of thecontrol devices; in response to displacement of one of the controldevices and in response to a decrease in engine load, storing anidentity and displacement direction of said displaced control device;and in response to displacement of the stored identity control device ina direction opposite to the stored displacement direction, temporarilyboosting the engine speed before operation of the correspondingauxiliary function can effect load on the engine.
 14. The method ofclaim 13, further comprising: in response to displacement of the storedidentity control device in a direction opposite to the storeddisplacement direction, temporarily decreasing a transmission ratio ofthe transmission.
 15. The method of claim 13, further comprising:monitoring the engine speed; and after the engine speed has beenboosted, if the engine speed drops below a threshold, increasing theamount by which the engine speed is boosted when the stored identitycontrol device is later displaced in the direction opposite to thestored displacement direction.
 16. The method of claim 13, furthercomprising: varying the amount by which the engine speed is boosted as afunction of a status of an operator controlled mode control device.